This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduce effects of sodium oxybate and zolpidem on an early morning nap to quantify pharmacological enhancement of specific sleep parameters in a dose-dependent manner. We will employ a within-subjects design with high and low doses of both drugs and placebo.